Cell Cycle + Replication

Question 1

Mitosis Promoting Factor (MPF)

Answer 1

Present in the cytoplasm of M cells

Induces mitosis

Activates protein kinase

Question 2

Why is MPF found in all eukaryotes?

Answer 2

it is highly conserved and essential for promoting mitosis

Question 3

Cyclin dependent kinase

Answer 3

an enzyme that catalyzes the transfer of a phosphate group

from ATP to a target protein

Question 4

Phospholyzation

Answer 4

the transfer of ATP to a target protein

catalyzed by protein kinase

target proteins need energy input to begin mitosis

Question 5

What happens when more cyclin is present?

Answer 5

MPF concentrations in the cytoplasm rise

target proteins are phospholyzed which initates mitosis

Question 6

When do MPF concentrations peak?

Answer 6

During M phase

Question 7

When do MPF concentrations rise?

Answer 7

During interphase

Question 8

What is the MPF composed of?

Answer 8

Cyclin and cyclin-dependent kinase bound together

Question 9

Cyclin

Answer 9

a regulatory protein that fluctuates in order to initiate M phase

it attaches to cdk’s to form MPF

therefore, when cyclin rises, MPF rises

Question 10

Concentration of cdk’s

Answer 10

remain constant

only cyclin fluctuates since cdk’s are hard to reproduce

Question 11

How many cyclin/cdk combos are there?

Answer 11

There are many combos that regulate the cell cycle for each phase

Question 12

G1 checkpoint

Answer 12

pass if cell size is adaquent, DNA is undamaged, nutrients are sufficient

Question 13

G0

Answer 13

mature cells do not pass the G1 checkpoint and enter into the G0 phase

Question 14

G2 checkpoint

Answer 14

pass if DNA is undamaged and has replicated successfully

activated MPF is present

Question 15

M checkpoint

Answer 15

chromosomes attatched to spindle apparatus

chromosomes have properly segregated and MPF is absent

Question 16

When do checkpoints occur?

Answer 16

At the end of phases

Make sure work supposedly to be done in certain phases is complete

Question 17

origin of replication

Answer 17

replication bubbles form at specific sequences of bases

Question 18

How many origins of replications do bacteria have?

Answer 18

Only one

That this why their DNA is circular

Question 19

How many origins of replications do eukaryotes have?

Answer 19

Many

Speeds up replication

Question 20

Where does active DNA synthesis take place?

Answer 20

At the replication fork

Question 21

Replication fork

Answer 21

Y-shaped region where the parental DNA double helix is separated into single strands and copied

Question 22

What direction does DNA have to be copied in?

Answer 22

5’ to 3’

Question 23

Why is DNA synthesis bidirectional?

Answer 23

2 replication forks going in both directions at the same time

Question 24

Helicase

Answer 24

breaks the hydrogen bonds between base pairs and opens the double helix at the replication fork

Question 25

Single-stranded DNA binding proteins

Answer 25

prevent the separated DNA strands from snapping back into place

Question 26

topiomerase

Answer 26

an enzyme that prevents supercoiling of DNA

Question 27

primer

Answer 27

an RNA strand that forms complimentary base pairs with the DNA template strand provides DNA polymerase with a 3' -OH group that can be used to form phosphodiester bonds

Question 28

Leading strand

Answer 28

strand that is synthesized toward the replication fork synthesized continuously

Question 29

Lagging strand

Answer 29

synthesized in a direction that is away from the moving replication fork synthesized in short Okazaki fragments has to readjust to go in 5' to 3' direction

Question 30

Primase

Answer 30

synthesizes a short stretch of RNA that works as a primer

Question 31

DNA polymerase I

Answer 31

removes the RNA primer and replaces it with DNA

Question 32

the end replication problem

Answer 32

there is no primer for DNA

Question 33

telomere

Answer 33

protective end of chromosomes TTAGG strand that is okay to loose due to end replication problem

Question 34

Is DNA polymerase bidirectional?

Answer 34

No. It is unidirectional

Question 35

Ligase

Answer 35

connects the fragments with phosphodiester bonds works on BOTH the leading and lagging strands

Question 36

How does telomerase work?

Answer 36

it extends the unreplicated end of DNA lays down a primer and following the primer TTAGG cap DNA is replicated to primer and the TTAGG cap is lost behind it, but that is alright

Question 37

When are telomeres added in the cell cycle?

Answer 37

during the S phase

Question 38

When are telomeres created?

Answer 38

During pre-natal development born with all the telomeres we get as we age, DNA becomes shorter